Abstract: A process for producing circuit boards involves the coating of a temporary substrate with a fluid mixture of an epoxy polymer component and a rubber polymer which is interactive therewith at temperatures of at least 180.degree. F. Preferably the rubber is a low molecular weight polyfunctional reactive butadiene/acrylonitrile interpolymer which is terminated by vinyl or carboxyl functional groups. The rubber component comprises at least 70 percent by weight of the epoxy polymer component, and the coating has a thickness of 0.001-0.015 inch. The coating is air dried upon the temporary substrate, and then the coating is transferred to the resinous substrate of the circuit board by heat and pressure. The coating is partially cured to effect partial polymerization of the epoxy prepolymer, further polymerization of the rubber, if it is of low molecular weight, and interaction of the rubber and epoxy polymer to form a matrix of the interacted rubber/epoxy.

Abstract: A process for producing circuit boards involves the coating of a resinous substrate with a fluid mixture of an epoxy polymer component and a rubber polymer which is interactive therewith at temperatures of at least 180.degree. F. Preferably the rubber is a low molecular weight polyfunctional reactive butadiene/acrylonitrile interpolymer which is terminated by vinyl or carboxyl functional groups. The rubber component comprises at least 70 percent by weight of the epoxy polymer component, and the coating has a thickness of 0.001-0.015 inch. The coating is partially cured to effect partial polymerization of the epoxy prepolymer, further polymerization of the rubber, if it is low molecular weight, and interaction of the rubber and epoxy polymer to form a matrix of the interacted rubber/epoxy. The exposed surface of this coating is then etched, and metal is deposited on the surface to form a conductive layer.

Abstract: A process for producing circuit boards involves the coating of a resinous substrate with a fluid mixture of an epoxy polymer component and a rubber polymer which is interactive therewith at temperatures of at least 180.degree. F. Preferably the rubber is a low molecular weight polyfunctional reactive butadiene/acrylonitrile interpolymer which is terminated by vinyl or carboxyl functional groups. The rubber component comprises at least 70 percent by weight of the epoxy polymer component, and the coating has a thickness of 0.001-0.015 inch. The coating is partially cured to effect partial polymerization of the epoxy prepolymer, further polymerization of the rubber, if it is low molecular weight, and interaction of the rubber and epoxy polymer to form a matrix of the interacted rubber/epoxy. The exposed surface of this coating is then etched, and metal is deposited on the surface to form a conductive layer.

Abstract: In order to enable fine traces to be obtained on printed circuit boards without excessive undercutting, while maintaining a high degree of adhesion, an unclad FRA board is provided with a surface butter coat which is etched to form a microporous surface layer. This layer is subjected to treatment in a plasma additively reactive with surface groups of the butter coat resin to provide modified groups promoting adherence to a thin metallization layer of vacuum deposited copper. The metallization layer is selectively electroplated to form the desired circuit pattern, and the unplated areas of the metallization layer are etched away.